Boron, aluminum and gallium perfluoro alkanesulfonate and resinsulfonate catalysts

ABSTRACT

Boron, aluminum and gallium C 1  -C 18  perfluoroalkanesulfonates (CF 3  (CF 2 ) n  SO 3 ) 3  M (M=B, A1, Ga; n=0-17) as well as perfluororesin sulfonates such as Nafionates are new, highly effective Friedel-Crafts catalysts. In contrast to volatile aluminum and boron trihalides, the Group III-B perfluoroalkanesulfonates are generally of low or no volatility and, except for boron triflate and some of its homologs, only sparingly soluble incommon organic solvents. This allows their use as solid or supported Friedel-Crafts catalysts of wide utility and scope in continuous heterogenous catalytic processes. At the same time, boron triflate and related lower perfluoroalkanesulfonates are particularly efficient soluble catalysts in solution reactions.

TECHNICAL FIELD

The present invention relates to a new class of boron, aluminum andgallium perfluoro alkanesulfonate or resinsulfonate Friedel-Craftscatalysts.

BACKGROUND OF THE INVENTION

In the course of more than 100 years of Friedel-Crafts chemistry, twocatalysts achieved preeminence. Anhydrous aluminum trichloride wasintroduced by Friedel and Crafts themselves and maintained its wide usedespite some of its unfavorable properties, i.e. it is a subliming solidwith only limited solubility in apolar or hydrocarbon solvents. Borontrifluoride became a significant catalyst since the 1930's based onfundamental studies by Meerwein and others. As it is a low boiling gas(bp. -100° C.), some of its more convenient complexes are frequentlyused, albeit reduced in reactivity, such as the ether complex. Althougha significant number of other Lewis acid halide (and pseudo halide)catalysts are also applied on occasion, none of them achleved similarwide applicatlon. Slnce the 1960's, superacidic catalysts based onantimony pentafluoride gained significance. Friedel-Crafts catalysts arewell reviewed (see G. A. Olah, "Friedel-Crafts Chemistry", WileyInterscience, New York, 1973; G. A. Olah, G. K. S. Prakash and J.Sommer, "Superacids", Wiley-Interscience, New York, 1986).

All the active Friedel-Crafts catalysts, such as the reactive halides ofboron, aluminum, and gallium, are substantially volatile or sublime andconsequently can not be used as solid or supported catalysts inheterogenous gas phase processes. This is a serious shortcoming ofFriedel-Crafts chemistry forcing it to be usually operated in closed,batchwise reactors. In contrast, the plurality of modern chemical andpetrochemical processes increasingly use heterogenous catalytic gasphase technology. My invention now discloses a new class of highlyefficient Friedel-Crafts catalysts which can also overcome thislimitation.

SUMMARY OF THE INVENTION

The invention relates to new, highly efficient Friedel-Crafts typecatalysts. In one embodiment, these catalysts comprise a Group III-Bmetal perfluoro alkanesulfonate. Also, perfluoro resin sulfonates may beused instead of perfluoro alkane sulfonates with similar results. Thepreferred group III-B metals include boron, aluminum and gallium, andthe carbon chain of the alkane group can range from 1 to 18 carbonatoms. These catalysts can be used alone or can be deposited on asuitable support.

The invention also relates to a process for effecting hydrocarbontransformations which comprises contacting a C₄ to C₃₀ hydrocarbon withthese catalysts. Continuous heterogeneous flow conditions are preferredfor effecting these transformations, which include reforming such asalkylation or isomerization, catalytic cracking, polymerization,halogenation, acylation, formylation, sulfonylation or nitration.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

I have discovered that a group III-B metal (i.e. boron, aluminum orgallium) perfluoroalkanesulfonate, such as thetris-trifluoromethanesulfonates (triflates) or higher homologousperfluoroalkanesulfonates are convenient and effective newFriedel-Crafts catalysts for use in continuous flow heterogeneoushydrocarbon conversion processes. Due to its monomeric nature, goodsolubillty and favorable physical properties and high reactivity, borontriflate (CF₃ SO₃)₃ B is the preferred catalyst of wide utility andgeneral use in solution chemistry. Aluminum (CF₃ SO₃)₃ Al and galliumtriflates (CF₃ SO₃)₃ Ga, on the other hand, are highly associated, highmelting compounds with low solubility. This renders their activity insolution chemistry somewhat limited, necessitating heterogeneousconditions, but they find excellent utility as solid or supportedheterogeneous catalysts for gas phase reactions.

Boron triflate was first prepared by Engelbrecht and Tshager intrifluoromethanesulfonic (triflic) acid solution as its conjugateBronsted-Lewis superacid, 2CF₃ SO₃ H-B(OSO₂ CF₃)₃. (Z. Anorg. Allgem.Chem. 1977, 19, 433). Olah, Laali and Farooq explored the catalyticactivity of this conjugate superacid (J. Org. Chem. 1983, 49, 4591).They also obtained boron triflate free of protic acids, but it was notfurther characterized nor was its catalytic activity studied. Collomb,Gandini and Cheradome (Macromol. Chem. Rapid Comm. 1980, 1, 489; Europ.Polym. Journ., 1980 16, 1135) reported the polymerization of somealkenyl monomers with metal perchlorates and triflates, which includedaluminum and gallium triflate. They assumed an ionic dissociationaccording to:

    2AlTf.sub.3 →AlTf.sub.2.sup.+ +AlTf.sub.4.sup.-

with AlTf₂ ⁺ initiating the polymerization of olefins by: ##STR1## Nosubstantiation for the suggested claims was provided and no similardissociation equilibrium is known even for aluminum halides. No teachingfor the use of Group III-B metal triflate catalysts in Friedel-Craftschemistry was made, nor were most of the higher homologperfluoroalkanesulfonates or polymeric perfluoroalkane sulfonatespreviously made and their catalytic use was never reported.

Boron triflate is conveniently prepared by reacting boron trichloride,boron tribromide or phenyldichloroborane with triflic acid. The reactionmust be carried out by adding the triflic acid to the boron halides andremoving in vacuum the hydrogen halides formed:

    MX.sub.3 +3CF.sub.3 SO.sub.3 H→M(OSO.sub.2 CF.sub.3).sub.3 +3HX

    C.sub.6 H.sub.5 MX.sub.2 +3CF.sub.3 SO.sub.3 H→M(OSO.sub.2 CF.sub.3).sub.3 +C.sub.6 H.sub.6 +2HX

M=B, Al, Ga.

Aluminum and gallium triflates can be similarly prepared, includingphenylaluminum (or phenyl gallium) sesquihalides.

The physical properties of boron triflate, which is a low melting (43°C.), relatively volatile solid, are very different from those ofaluminum and gallium triflates which are high melting point, powderysolids (mp.>350° C.). Boron triflate is extremely hygroscopic and wellsoluble in many solvents including such as methylene chloride,1,1,2-trichlorotrifluoromethane (Freon-13), SO₂, SO₂ ClF, nitromethane,etc. Aluminum and gallium triflates, in contrast are not soluble in mostof these solvents and show only very limited solubility in SO₂, SO₂ ClFand nitromethane. Both aluminum and gallium triflate, however, aresoluble in highly coordinating solvents such as acetonitrile.

Higher perfluoroalkanesulfonates of 2 to 18 carbon atoms such asperfluorobutyl, -hexyl, -octyl, -decyl, -dodecyl and -octadecylsulfonates are similarly prepared from the corresponding sulfonic acids.

    3CF.sub.3 (CF.sub.2).sub.n SO.sub.3 H+MX.sub.3 →((CF.sub.3 CCF.sub.2).sub.n SO.sub.3).sub.3 M+3MX

M=B, Al, Ga, X=Cl, Br, n=1-17.

They show decreasing solubility with increasing molecular weight inaccordance with behavior of their single carbon triflate analogs.

The catalysts of the invention can be used in solution, in a dispersionof solvents, or as solid or supported catalysts under conditionscustomary in homogeneous and heterogeneous catalysis.

Perfluorinated resinsulfonic acids also can be reacted with Group III-Bmetal halides (preferably chlorides or bromides) to obtain thecorresponding metal resin sulfonates.

Perfluoroalkanesulfonic acid polymers were first developed by the DuPontCompany. They are copolymers of perfluorovinyl ethers and perfluorovinylsulfonic acids. The acidic form of the resin, Nafion-H, is a widely usedsolid superacid catalyst in synthesis (for a review, see G. A. Olah, P.S. Iyer and G. K. S. Prakash, "Synthesis", 1986, 513-531).

This catalyst comprises a perfluorinated polymer having sulfonic acidgroups in the amount of about 0.01 to 5 mequiv/gram catalyst. Thepolymer catalyst contains a repeating structure which can be depictedas: ##STR2## where the ratio of x over y varies from about 2 to about50, and m is 1 or 2. Polymer sulfonic acids of the above structure canbe prepared in various ways. One method, disclosed in Conolly et. al.,U.S. Pat. No. 3,282,875 and Cavanaugh et. al., U.S. Pat. No. 3,882,093,comprises polymerizing the corresponding perfluorinated vinyl compounds.It is also possible to prepare polymer catalyst according to U.S. Pat.No. 4,041,090 by copolymerizing the corresponding perfluorinated vinylethers with perfluoroethylene and/or perfluoro-alpha-olefins.

Group III-B metal Nafionates are prepared by reacting the free sulfonicacid resin (Nafion-H) with the corresponding metal chloride (bromides)and recovering the hydrogen halides formed in vacuum. ##STR3##

It is also possible that certain Group III-B metal sites contain onlyone or two attached Nafionates and are thus mixed halide Nafionates ofthe type

    Naf MX.sub.2 or Naf.sub.2 MX X=Cl, Br

although at the clustering sites, metal tris-Nafionates are probable.

Other perfluorinated polymer sulfonic acids capable of givingcatalytically active Group III-B metal salts include resinsulfonic acidsanalogous to Nafion, such as polytrifluoroethylenesulfonic acids andtetrafluoroethylenetrifluoroethylenesulfonic acid polymers.

The catalyst of the invention may be absorbed on a suitable supportmaterial alumina, silica or mixtures thereof as well as other chalcidescan be used for this purpose.

All metal perfluoroalkanesulfonate catalysts were characterized throughtheir nuclear magnetic resonance including ¹¹ B, ¹³ C, ¹⁹ F, ²⁷ Al andGa and infrared spectroscopic spectra.

The catalytic activity of Group III-B perfluoroalkanesulfonates isillustrated by, but not limited to, such typical Friedel-Craftsreactions as alkylation, acylation, isomerization, cracking,polymerization, halogenation and the like. It is considered that allreaction types summarized and discussed in my monographs "Friedel-Craftsand Related Reactions", Vols. I-IV, Wiley-Interscience, New York,1963-64, and "Friedel-Crafts Chemistry", Wiley-Interscience, New York,1973, are advantageously catalyzed by the disclosed new catalyst of mypresent invention. Thus, the disclosures of these documents areexpressly incorporated herein by reference.

Hydrocarbon reforming processes, such as alkylation and isomerization,as well as de- and transalkylations, disproportionation, polymerization,cracking and related processes of hydrocarbons, are readily catalyzed bythe catalysts of the present invention as described herein above. Theseprocesses are effected by contacting a charge of a hydrocarbon, orhydrocarbon mixture with the above described catalysts under theconventional conditions of the desired hydrocarbon conversion.Contacting of the catalyst with the hydrocarbon charge is facilitated byusing such conventional systems as fixed bed systems, moving bedsystems, fluidized bed systems, continuous or batch-type operations. Thehydrocarbon conversions utilizing the presently described catalysts canbe carried out either in the vapor phase, in the liquid phase, or asmixed phase operations. Conversions can also be carried out in thepresence of hydrogen, or catalysts generally also cause concurrentcleavage reactions (cracking).

Alkylations can be particularly effectively carried out employing thecatalysts of the present invention.

Aromatic and aliphatic hydrocarbons such as benzene, toluene,alkylbenzenes, naphthalene and the like, or straight chain or branchedalkanes including methane, ethane, propane, butanes, pentanes, hexanes,etc., cycloalkanes and polycyclic alkanes, including adamantane anddiamantane, as well as alkenes and alkynes are effectively alkylated byalkyl halides, olefins or other alkylating agents both in solutionchemistry and in the gas phase reactions catalyzed by Group III-B metalperfluorosulfonate catalysts of my invention.

Alkylation of alkylatable hydrocarbons such as alkanes or aromatics witholefins, alkyl halides, alcohols, and other alkylating agents can beeffected in the presence of the catalyst at temperatures between about0° to about 200° C. and the pressure between about atmospheric and 50atmospheres.

The catalysts of the present invention are also suitable for catalyticcracking of hydrocarbons. The hydrocarbon charge may comprise normalalkanes or complex mixtures of alkanes, naphthenes, and aromatics, suchas they occur in petroleum, which is the feed normally used incommercial catalytic cracking units. Hydrocarbon cracking utilizingcatalysts of the present invention can be conducted at temperaturesranging between 50° and 250° C. and pressures from atmospheric to 50atmospheres or higher. Presence of hydrogen (hydrocracking) can beapplied to further prolong catalyst life and, thus, cause more efficientcracking operations. In the use of the catalysts of the presentinvention for hydrocarbon conversion reactions hydrogen gas ornaphthenic hydrocarbons can be used as moderators, which tend todecrease any concurrent cracking reactions. Operation in the presence ofhydrogen and related hydrocarbon moderators are also particularlyadvantageous for isomerizations.

Isomerization of isomerizable C₄ to C₃₀ hydrocarbons, such as alkanes,naphthenes or alkyl-aromatic hydrocarbons may be effectively carried oututilizing the catalyst of this invention. Isomerization ofstraight-chain or slightly branched-chain alkanes containing 4 or morecarbon atoms in their molecules, such as n-butane, n-pentane, n-hexane,n-heptane, n-octane, and the like, may be readily effected. Likewise,cycloalkanes containing at least 5 carbon atoms in the ring, such asalkyl cyclopentanes and cyclohexanes are effectively isomerized. Theseisomerizations are particularly suitable to produce high octane numberbranched alkane mixtures of the gasoline range. As examples ofcommercial mixtures, straight-run type or light naphtha fractions fromconventional refinery operations can be mentioned. Isomerization ofalkylbenzenes include those of xylenes, diethylbenzenes, cymenes, andother di- and poly-alkylbenzenes.

In carrying out isomerizations of isomerizible C₄ to C₂₀ hydrocarbons,contact between the catalyst and hydrocarbon charge is conducted attemperatures between about 0° and 300° C., preferably between 25° and200° C., at pressures between atmospheric and 50 atmospheres or more.The hydrocarbon is passed over the catalyst as a gas or liquid generallyadmixed with hydrogen, with a liquid hourly space velocity generallybetween about 0.5 and 5.0 or a gaseous hourly space velocity between 50and 5000. The resulting product is withdrawn from the reactor, and isseparated by any suitable means such as fractional distillation. Anyunreacted starting material may be recycled. The effective hydrocrackingcatalysts, based on this invention are not effected by the presence ofsulfur and other impurities, and which normally cause rapid deactivationof conventional cracking catalysts. In view of the need of increasedutilization of "heavy" petroleums and lower grade crudes, the newcatalysts and process of this invention are of considerable commercialsignificance.

Catalysts of the invention are also effective for ring openingpolymerizations such as of tetrahydrofuran and alkene oxides and otherpolymers adaptable for cationic polymerizations.

Friedel-Crafts acylations of aromatic and aliphatic hydrocarbonsincluding formylation, acetylation, propionylation, benzoylation and thelike are also catalyzed by the disclosed catalysts.

Aromatic and aliphatic hydrocarbons are also nitrated with nitrylchloride or nitrogen oxides and sulfonylated with alkyl or aryl sulfylhalides in the presence of the Group III-B perfluoroalkanesulfonatecatalysts. The nitration and acylation reactions can be carried outunder the same conditions as for the isomerization reactions describedabove.

Catalytic halogenation (chlorination, bromination or iodination) ofaromatic and aliphatic hydrocarbons takes places with ease and highselectivity. Noteworthy is the chlorination and bromination of methanewhich can be effected in solution or in the gas phase over aluminumtriflate, supported boron triflate or related catalysts at temperaturesbetween 20° to 250° C. giving selectively monohalogenationcharacteristic of electrophilic reactions as contrasted withnon-selective radical reactions.

Other applications of the catalysts of present invention towardsadditional conversions of hydrocarbons should be apparent to thoseskilled in the art of hydrocarbon chemistry.

EXAMPLES

The scope of the invention is further described in connection with thefollowing examples, which are set forth for the purpose of illustrationand are not to be considered to limit the scope of the invention in anymanner.

EXAMPLE 1

Aluminum tris-triflate (CF₃ SO₃)₃ Al is prepared by placing apremeasured amount of anhydrous aluminum trichloride (tribromide) in awell dried three necked flask equipped with a magnetic stirrer, apressure equalizing dropping funnel and dry nitrogen inlet. The flask iscooled and 3 equivalents of triflic acid are slowly added from thedropping funnel with efficient stirring whereby HCl (HBr) slowlyevolves. The temperature was slowly raised until completion of thereaction. The flask is then evacuated in vacuum to remove any HX andresidual triflic acid giving aluminum triflate as a slightly off coloredsolid.

EXAMPLE 2

(C₄ F₉ SO₃)₃ Al and (C₁₀ F₂₁ SO₃)₃ Al were prepared from thecorresponding perfluoroalkanesulfonic acids as in Example 1.

EXAMPLE 3

To boron tribromide (1 equivalent) placed in a three necked flask wasslowly added 3 equivalents of triflic acid and preparation carried outas in Example 1 giving boron tris-triflate (CF₃ SO₃)₃ B as a colorlesslow melting solid (mp 43° C.).

EXAMPLE 4

To gallium trichloride (1 equivalent) was added 3 equivalents of triflicacid and preparation carried out as in Example 1 to give galliumtris-triflate (CF₃ SO₃)₃ Ga.

EXAMPLE 5

Benzene (5 equivalents) was reacted in a batchwise stirred alkylationapparatus protected from moisture in the presence of 0.2 equivalents ofboron triflate catalyst with 1.5 equivalents ethylene gas. Thetemperature was controlled as to keep it at about 50° C. Work-up gave1.2 equivalents of ethylbenzene with diethylbenzenes and some higheralkylates amounting to 0.3 equivalents.

EXAMPLE 6

Aluminum triflate was placed in the reaction tube of a heterogeneous gasphase alkylation reactor and a mixture of 2 equivalents of benzene and 1equivalent of ethylene was continuously passed through the catalyst at atemperature of about 150° C. with a gas liquid hourly space velocity(ml/g-hr) of 250. The alkylation product contained an average of 0.6equivalents of ethylbenzene and 0.13 equivalents of dialkylbenzenes.

EXAMPLE 7

A 2:1 equivalent mixture of benzene and propylene was passed over acatalyst comprised of 5% boron triflate supported on charcoal in acontinuous tube reactor at a temperature of 145° C. and GHSV of 250.Product composition was 0.47 equivalents of cumene and smaller amountsof diisopropyl benzenes.

EXAMPLE 8

0.015 equivalents of boron triflate dissolved in methylene chloride wasreacted with 1 equivalent of toluene and 0.5 equivalents of1-chloroadamantane at 30° C. for 15 minutes. Upon usual work-up, 0.38equivalents of methyl adamantylbenzenes were obtained composed of about54% of meta isomer, 37% of para, and 9% ortho isomer.

EXAMPLE 9

1 equivalent of normal butane was reacted in a pressure autoclave in thepresence of 0.1 equivalents of boron triflate dissolved in Freon 113(1,1,2-trichlorotrifluoroethane) at 50° C. for 1 hour. Gas liquidchromatographic analysis of the products showed formation of 0.4equivalents of isobutane with small amounts of propane and pentanes.

EXAMPLE 10

Reaction was carried out as in Example 8, but with boron trisperfluorobutanesulfonate as catalyst. 0.27 equivalents of isobutane wasobtained.

EXAMPLE 11

1 equivalent of a mixture of exo- and endo- trimethylenenorbornane(tetrahydrodicyclopentadiene) was reacted with 0.2 equivalents of borontris-triflate catalyst in Freon 113 solution at room temperature for 12hours. A nearly quantitative yield of 0.98 equivalents of adamantane wasobtained with no byproducts.

EXAMPLE 12

A 2:1 molar equivalent mixture of methane and chlorine was passed over a5% aluminum triflate supported on charcoal catalyst at 150° C. in acatalytic tube reactor. The product obtained contained 97% methylchloride and 3% methylene chloride with a 38% chlorine conversion.

EXAMPLE 13

Previously dried and distilled tetrahydrofurane (THF) was stirred in areaction flask protected from moisture and air with 0.02 equivalents ofaluminum tris-triflate. After an initiation period of about 1 hour,polymerization takes place giving an increasingly viscous reactionmixture. Portions of additional THF can be now added till a total of 5equivalents were polymerized. Work-up gave a transparent polymethyleneether polymer. Molecular weight reached 1.5×10⁶.

EXAMPLE 14

Benzene (1 equivalent) was reacted with acetyl chloride (0.5equivalents) in the presence of 0.25 equivalents of gallium triflatecatalyst at 50°-60° C. for 1 hour giving 0.35 equivalents ofacetophenone.

While it is apparent that the invention herein disclosed is wellcalculated to fulfill the desired results, it will be appreciated thatnumerous modifications and embodiments may be devised by those skilledin the art, and it is intended that the appended claims cover all suchmodifications and embodiments as fall within the true spirit and scopeof the present invention.

What is claimed is:
 1. A process for effecting hydrocarbon reformingwhich comprises contacting a C₄ to C₃₀ hydrocarbon with a Friedel-Craftscatalyst comprising a boron, aluminum, or gallium perfluoroalkanesulfonate at suitable reforming temperature and pressure conditions andfor a time sufficient to effect said hydrocarbon reforming.
 2. Theprocess of claim 1 wherein the reforming is effected under continuousheterogenous flow conditions at a temperature between about 0° and 300°C. and at a pressure between about atmospheric and 50 atmospheres. 3.The process of claim 2 wherein the hydrocarbon reforming includes analkylation or an isomerization reaction.
 4. A process for effectinghydrocarbon reforming which comprises contacting a C₄ to C₃₀ hydrocarbonwith a Friedel-Crafts catalyst comprising a boron, aluminum or galliumsalt of one of a perfluorinated polymeric resinsulfonic acid, apolytrifluoroethylene-sulfonic acid, or atetrafluoroethylene-trifluoroethylene-sulfonic acid copolymer atsuitable reforming temperature and pressure conditions and for a timesufficient to effect said hydrocarbon reforming.
 5. The process of claim4 wherein the conversion reforming is effected under continuousheterogeneous flow conditions at a temperature between about 0° and 300°C. and at a pressure between about atmospheric and 50 atmospheres. 6.The process of claim 5 wherein the hydrocarbon reforming includes analkylation or an isomerization reaction.
 7. An alkylation process whichcomprises passing an alkylatable C₄ to C₃₀ hydrocarbon and an alkylatingagent over a Friedel-Crafts catalyst comprising a boron, aluminum orgallium perfluoroalkane sulfonate to effect a continuous heterogenousflow alkylation of said hydrocarbon at a temperature between 0° and 200°C., a pressure between atmospheric and 50 atmospheres and for a timesufficient to effect said alkylation.
 8. The process of claim 7 whereinsaid catalyst comprises a boron, aluminum or gallium salt of one of aperfluorinated polymeric resin sulfonic acid, apolytrifluoroethylene-sulfonic acid, or atetrafluoroethylenetrifluoroethylene-sulfonic acid copolymer.
 9. Anisomerization process which comprises passing C₄ to C₃₀ hydrocarbon overa Friedel-Crafts catalyst comprising a boron, aluminum, or galliumperfluoroalkane sulfonate to effect a continuous heterogenous flowisomerization of said hydrocarbon at a temperature between 0° and 300°C., a pressure between atmospheric and 50 atmospheres and for a timesufficient to effect said isomerization.
 10. The process of claim 7wherein said catalyst comprises a boron, aluminum or gallium salt of oneof a perfluorinated polymeric resin sulfonic acid, apolytrifluoroethylene-sulfonic acid, or atetrafluoroethylenetrifluoroethylene-sulfonic acid copolymer.